Android database optimization and Android database Optimization

Android database optimization and Android database Optimization

1. Optimize database insertion through one compilation and transaction, and optimize database query by querying only specified fields.

/*** <Ol> <li> open database * <li> Create sentence (avoid String + String) * <li> compile (avoid multiple compilations) * <li> run * <li> close database </ol> * @ author shixin */public class MainActivity extends Activity {List <String> list = new category List <String> (); arrayAdapter <String> arrayAdapter; SQLiteDatabase db; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); ListView listVi Ew = (ListView) findViewById (R. id. listView); arrayAdapter = new ArrayAdapter <String> (this, android. r. layout. simple_list_item_1, list); listView. setAdapter (arrayAdapter); // Create a memory backed SQLite database. its contents will be destroyed when the database is closeddb = SQLiteDatabase. create (null); // Execute a single SQL statement that is NOT a SELECT or any other SQL statement that returns datadb. ExecSQL ("create table life (plant text, animal text)") ;}@ Overrideprotected void onDestroy () {super. onDestroy (); db. close ();} public void onClick (View v) {switch (v. getId () {case R. id. btn_insert: try {db. beginTransaction (); String [] [] lifes = {"potato", "tomato", "apple" },{ "rat", "cat ", "dog" }}; SQLiteStatement stmt = db. compileStatement ("insert into life values (?,?) "); For (int I = 0; I <lifes [0]. length; I ++) {stmt. clearBindings (); stmt. bindString (1, lifes [0] [I]); stmt. bindString (1, lifes%1% I %%%%stmt.exe cuteInsert ();} db. setTransactionSuccessful ();} catch (Exception e) {} finally {db. endTransaction ();} break; case R. id. btn_query: // only query the required fields more efficiently. Cursor c = db. query ("life", new String [] {"plant"}, null, null); while (c. moveToNext () {list. add (c. getString (c. getColumnIndex ("plant");} c. close (); // make the ListView update display arrayAdapter. notifyDataSetChanged ();}}}